#!/usr/bin/python

"""Project Euler Solution 002

Copyright (c) 2011 by Robert Vella - robert.r.h.vella@gmail.com

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
"""

import cProfile
from euler.numbers.number_theory import FibonacciList
from itertools import takewhile

def get_answer():
    """Question:
    
    Each new term in the Fibonacci sequence is generated by adding 
    the previous two terms. By starting with 1 and 2, the first 10 
    terms will be:

    1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...

    By considering the terms in the Fibonacci sequence whose values 
    do not exceed four million, find the sum of the even-valued terms.
    """
    
    #Cache for Fibonacci numbers.
    fibs = FibonacciList()
 
    #Return result
    return sum(
              takewhile(
                        lambda fib : fib < 4000000,
                        (fib for fib in fibs if fib % 2 == 0)
                    )
            )

if __name__ == "__main__":
    cProfile.run("print(get_answer())")
